Due to the ongoing issue with git-lfs package, the apt-get update command is failing on Semaphore.
The issue on the git-lfs repository:https://github.com/git-lfs/git-lfs/issues/4294#issuecomment-878778071
Our team is working on mitigating this problem and the repository in question will soon be removed from the image.
In the meantime, we suggest this quick workaround for fixing your workflows:
Before running the apt-get update command run the following command in your job:
sudo rm -f /etc/apt/sources.list.d/github_git-lfs.list